A Customs war, also known as a toll war or tariff war, is a type of economical conflict between two or more states. In order to pressure one of the states, the other raises taxes or tariffs for some of the products of that state. As a reprisal, the latter state may also increase the tariffs.
One example of a modern tariff war occurred in the 1920s and 1930s between the Weimar Republic and Poland, in the German–Polish customs war. The Weimar Republic, led by Gustav Stresemann wanted to force Poland, by creating an economic crisis by increasing the tolls for coal and steel products developed there, to give up its territory. As a reprisal, the Poles increased toll rates for many German products. This led to fast development of the port of Gdynia, which was the only way Poland could export its goods to Western Europe without having to transport them through Germany.
In September 1922 the Fordney–McCumber Tariff (named after Joseph Fordney, chair of the House Ways and Means Committee, and Porter McCumber, chair of the Senate Finance Committee) was signed by U.S. President Warren G. Harding. In the end, the tariff law raised the average American ad valorem tariff rate to 38 percent.
Trading partners complained immediately. Those injured by World War I said that, without access by their exports to the American market, they would not be able to make payments to America on war loans. But others saw that this tariff increase would have broader deleterious effects. Democratic Representative Cordell Hull said, "Our foreign markets depend both on the efficiency of our production and the tariffs of countries in which we would sell. Our own [high] tariffs are an important factor in each. They injure the former and invite the latter."